Tabulated reflection values

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StompinTom
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Tabulated reflection values

Post by StompinTom » Sat Jan 22, 2022 4:52 am

Hello!

Is it possible to define tabulated reflection values for specular materials, or some other combination of materials for this? We have a client that has particular reflectance data that they want to represent, and specular materials seem to only reflect uniformly. I attach a sample photo of the type of glass I am talking about.

I took a look at some of the Saint Gobain glass materials on the Indigo website (such as this one: https://www.indigorenderer.com/materials/materials/1069) however there is a large chunk of <private_data> which I believe hides the way it does the colored reflection.

Is there any documentation for this or any tips on achieving more control over the reflection color? The client can provide both tabulated data as well as L*a*b* values for their product.


Thanks!

Tom
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thesquirell
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Re: Tabulated reflection values

Post by thesquirell » Sun Jan 23, 2022 9:27 am

Shouldn't you be able to recreate the tabulated data in the tabulated tab<-absorption, from the medium of your specular shader?

Also, that private data is just 401 values from 380 to 780nm in the scale close to 24.

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pixie
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Re: Tabulated reflection values

Post by pixie » Mon Jan 24, 2022 1:29 am

StompinTom wrote:
Sat Jan 22, 2022 4:52 am
however there is a large chunk of <private_data> which I believe hides the way it does the colored reflection.
I think that is due being ip of Saint-Gobain

StompinTom
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Re: Tabulated reflection values

Post by StompinTom » Mon Jan 24, 2022 10:46 pm

thesquirell wrote:
Sun Jan 23, 2022 9:27 am
Shouldn't you be able to recreate the tabulated data in the tabulated tab<-absorption, from the medium of your specular shader?
The absorption part is fine, however I don't see how to create a tabulated parameter for the reflection of specular materials.
thesquirell wrote:
Sun Jan 23, 2022 9:27 am
Also, that private data is just 401 values from 380 to 780nm in the scale close to 24.
I'm not sure I understand this... what kind of scale are you referring to? Do you have any simple examples I could look at?
Otherwise, even setting a simple RGB reflection color would be a good start!
pixie wrote:
Mon Jan 24, 2022 1:29 am
I think that is due being ip of Saint-Gobain
I understand the <private_data> section of those materials specifically is Saint-Gobain's IP, however it would be good to know how to generate one's own <private_data> in order to simulate a differently colored reflectance. It looks like Indigo is able to do that, so it would be great to unlock and understand those capabilities :D

StompinTom
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Re: Tabulated reflection values

Post by StompinTom » Mon Jan 24, 2022 11:00 pm

Searching the forum, I see that it is @galinette that is behind the Saint-Gobain development:
saint-gobain-glass wrote:
Tue Feb 28, 2012 1:30 am
Dear Indigo users,

During these last two years, Saint-Gobain Glass R&D worked with Glare on architectural coated glass rendering. We developed specific proprietary material models to provide an exact description of the complex interactions between the coating and the glass.

You can find example images of one coating below.

We will release these materials very soon, so that Indigo users may render glass buildings with extremely realistic coating models. They will contain a proprietary encrypted model of the glass spectral response.

Best regards,

Etienne Sandré-Chardonnal
Saint-Gobain Recherche
I remember seeing those discussions before, but haven't seen anything since in terms of documentation or other ways of affecting the reflection of specular materials.

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